import { transform } from "stream-transform";

transform(
  [
    ["1", "2", "3", "4"],
    ["a", "b", "c", "d"],
  ],
  function (data, callback) {
    setImmediate(function () {
      data.push(data.shift());
      callback(null, data.join(",") + "\n");
    });
  },
  {
    parallel: 20,
  },
).pipe(process.stdout);

// Output:
// 2,3,4,1
// b,c,d,a
